I know, I know....Another thread about headers.

All I want to talk about or hear about are "true long tube" headers.
NOT Kooks or ARH...as they ARE NOT true long tube headers!!!

Namely: LG PROS....VS.....DYNATECH, etc...

Both are very similar in setup, etc. What about construction, fittings, quality, welds, etc...Is either setup higher quality...more stainless steel?

Does anyone out there have dyno sheets for a C5 Z06 with the Dynatech's compared to the LG Pros????

Any other information about Dynatech's??? What about the power down low for street driving??? I currently have LG Pros on my Z06 and am considering replacing them with another true long tube header.

Chime in quick!!! Oh...and Happy Thanksgiving!!

 

I was under the impression that the LG Pros were the best LT header you can buy for the C5 Z. I'm saving up alittle more cash and buying only the LG's.

Interested in the responses .

Patrick

 

I also think it would be of little benefit to change from LG Pros to something else.
They are all pretty close in power, so the $1500 you'd be spending could be put towards other mods.
Just my 2cents.

 

 

What do you mean by Kooks aren't "true" long tube headers?

 

I love my LG pros. Construction, welds and fit were perfect. Great power and sound with my borla stingers. Dyno #'s in sig.

 

LG Pro's Here too, dyno in sig.

 

they fall more under mid-length headers.

 

Both the Dynatechs and LG pro's are very well built, with the edge in quality costruction going to Dynatech, IMHO. Most people believe that the LG's make a bit more power and low end torque because of their "merge collectors". Either header for a C5 is going to get you some decent power gains, and another LT you might consider is the Stainless Works system and also the Melrose Headers. They are also high quality "true long tubes". Hope this helps!

Jimbo

 

The LG Pro Long Tubes are the best in my opinion. I researched this out before I bought. Go to LS1tech.com as they have all kinds of comparisons on there from guys (Search as they have dyno charts posted). Granted, they are more money, but they do put our a little more HP and more importantly more torque. LG Long Tubes are made by Borla.

Not that the other brands are bad, because they are not. Mallett Custom headers are made by Stainless Works, LPE uses Kooks or AR, and obviously Phil at DTE uses his brand.

Again, I would get the LG's.

JG853

 

Yes, I would have to agree...ARH and Kooks are more of a mid length header. What do you think about the placement of the X pipe on the ARH headers. Doesn't the placement right after the merge collectors and before the cats defeat the purpose. From my understanding, the X is supposed to help scavenge the gases when they start to cool. This would mean after the cats.

I think the dynatechs look pretty nice. I just wonder why they are not as popular as some of the others.

 

Anyone have O2 sensor issues with the LG's?
I've been told that O2 sensors don't last long in the LG set up.

Question: Why wouldn't LPE use either one of these set ups (LG/Dynatech) if they were "better"............anyone know what their reasoning is?

 

Competitors brands - LG / DTE just do not manufacture product, they also have services like LPE.

JG853

 

My 02 sensors have been just fine. No problems at all.

Check LS1tech.com and view the results. People use LG's because they are proven to give more power and torque. They are for the guys that want ever possible bit of HP and torque out of their car. If this is not the overriding factor for you, then go for one of the other brands.

JG853

 

My understanding was that the placement of the x-pipe before the midpipe provided more scavenging, which is why some people are switching to ARH, especially in the FI arena?

 

I've got to weigh in here because I believe the best headers for our beloved 346 c.i. motor are 30-33 inches in primary tube length with 6-12 inches of total collector length. I'm aware of only two brands meeting that criteria and they are LG and Dynatech.

Tuning as many cars as I've seen over the years I can easily say that both brands are also the performances leaders.

Here's a little information that you can read through and possibly shed some more light on the selection process as well as the performance side of exhaust...credit goes to my good freinds at Veltune...




Exhaust Theory and Header Primer

This information is the result of several decades of research and experimentation. It was compiled from various sources including the author’s personal experience and theories as a pipe fabricator and drag racer. Considerable effort has been invested to assure it's technical accuracy. It is a work-in-progress that is updated as relevant data presents itself. It was written non-mathematically to facilitate an overall understanding of exhaust physics and to elicit more theory in the quest for higher performance.


Introduction

No header/exhaust system is ideal for all applications. Depending on their design and purpose, all headers compromise something to achieve something else. Before performing header or other exhaust modifications to increase performance, it is critical to determine what kind of performance you want.

• Do you want the best possible low-end power, the best mid-range power or maximum top-end power?
• Do you plan to use nitrous oxide or forced induction (supercharger or turbocharger)?
• Are you going to increase displacement?
• Will you be using an aftermarket cam with different lift, duration, timing and overlap?
• Do you understand the relationship between torque (force) and horsepower (amount of work within time)?
• Can you distinguish between cosmetic headers and performance headers?
• Have you considered vehicle weight, transmission (stall speed, if applicable) and gear ratios?

Without careful thought about these variables, a header/exhaust system can yield very disappointing results. Conversely, a properly designed system that is well-matched to the engine can provide surprising power gains.

The distinction between "maximum power" and "maximum performance" is significant beyond conversational semantics. Realistically, one header may not produce both maximum power and maximum performance. For a vehicle to cover "X" distance as quickly as possible, it is not the highest peak power generated by the engine that is most critical. It is the highest average power generated across the distance that typically produces the quickest time.

When comparing two horsepower curves on a dynamometer chart (assuming other factors remain constant), the curve containing the greatest average power is the one that will typically cover the distance in the least time and that curve may, or may not, contain the highest possible peak power.

In the strictest technical sense, an exhaust system cannot produce more power on its own. The potential power of an engine is determined by the amount of fuel available for combustion. More fuel must be introduced to increase potential power. However, the efficiency of combustion and engine pumping processes is profoundly influenced by the exhaust system.

A properly designed exhaust system can reduce engine pumping losses. Therefore, the design objective for a high performance exhaust is (or should be) to reduce engine-pumping losses, and by so doing, increase volumetric efficiency. The net result of reduced pumping losses is more power available to move the vehicle. As volumetric efficiency increases, potential fuel mileage also increases because less throttle opening is required to move the vehicle at the same velocity.

Much controversy (and apparent confusion) surround the issue of exhaust "back-pressure". Many performance-minded people who are otherwise well-enlightened still cling tenaciously to the old cliché.... "You need some back-pressure for best performance."

For virtually all high performance purposes, backpressure in an exhaust system increases engine-pumping losses and decreases available engine power. It is true that some engines are mechanically tuned to "X" amount of backpressure and can show a loss of low-end torque when that backpressure is reduced. It is also true that the same engine that lost low-end torque with reduced back-pressure can be mechanically re-tuned to show an increase of low-end torque with the same reduction of back-pressure. More importantly, maximum mid-to-high RPM power will be achieved with the lowest possible backpressure. Period!


The objective of most engine modifications is to maximize air and fuel flow into, and exhaust flow out of the engine. The inflow of an air/fuel mixture is a separate issue, but it is directly influenced by exhaust flow, particularly during valve overlap (when both valves are open for "X" degrees of crankshaft rotation). Gasoline requires oxygen to burn. By volume, dry, ambient air at sea level contains about 21% oxygen, 78% Nitrogen and trace amounts of Argon, CO2 and other gases. Since oxygen is only about 1/5 of air’s volume, an engine must intake 5 times more air than oxygen to get the oxygen it needs to support the combustion of fuel. If we introduce an oxygen-bearing additive such as nitrous oxide, or use an oxygen-bearing fuel such as nitromethane, we can make much more power from the same displacement because both additives bring more oxygen to the combustion chamber to support the combustion of more fuel. If we add a supercharger or turbocharger, we get more power for the same reason…. more oxygen is forced into the combustion chamber.


Theoretically, in a normally aspirated state of tune without fuel or oxygen-rich additives, an engine’s maximum power potential is directly proportional with the volume of air it flows. This means that an engine of 350 cubic inches has the same maximum power potential as an engine of 454 cubic inches, if they both flow the same volume of air. In this example, the powerband characteristics of the two engines will be quite different but the peak attainable power is essentially the same. In view of this, the author has amended the old hot rod proverb "There's no substitute for cubic inches." to include..... "except more efficiency!"
________________________________________

Flow Volume & Flow Velocity

One of the biggest issues with exhaust systems, especially headers, is the relationship between gas flow volume and gas flow velocity (which also applies to the intake track). An engine needs the highest flow velocity possible for quick throttle response and torque throughout the low-to-mid range portion of the power band. The same engine also needs the highest flow volume possible throughout the mid-to-high range portion of the powerband for maximum performance. This is where a fundamental conflict arises. For "X" amount of exhaust pressure at an exhaust valve, a smaller diameter header tube will provide higher flow velocity than a larger diameter tube. Unfortunately, the laws of physics will not allow that same small diameter tube to flow sufficient volume to realize maximum possible power at higher RPM. If we install a larger diameter tube, we will have enough flow volume for maximum power at mid-to-high RPM, but the flow velocity will decrease and low-to-mid range throttle response and torque will suffer. This is the primary paradox of exhaust flow dynamics and the solution is usually a design compromise that produces an acceptable amount of throttle response, torque and horsepower across the entire powerband.


A very common mistake made by some performance people is the selection of exhaust headers with primary tubes that are too large in diameter for their engine's state of tune. Bigger is not necessarily better and is often worse.
________________________________________
Equal Length Primary Tubes

The effectiveness of equal length header tubes is widely debated.
Assuming that a header is otherwise properly designed (and many headers are not), equal length primary tubes offer some benefits that are not present with unequal length tubes. The benefits are smoother engine operation, tuning simplicity and increased low-to-mid range torque.

If the header tubes are not equal length (most commercial headers are not equal length), both inertial scavenging and wave scavenging will vary among engine cylinders, often dramatically. This, in turn, causes different tuning requirements for different cylinders. These variations affect air/fuel mixtures and timing requirements, and can make it very difficult to achieve optimal tuning. Equal length header tubes eliminate these exhaust-induced difficulties. "Tuning", in the context used here, does not mean installing new sparkplugs and an air filter. It means configuring a combination of mechanical components to maximum efficiency for a specific purpose and it can not be overemphasized that such tuning is the path to superior performance with a complex system of parts that must work together in a complimentary manner.


If a header is otherwise properly designed for its application, equal length header tubes are, of necessity, longer than unequal length tubes. The lengths of both primary and collector tubes strongly influence the location of the torque peak(s) within the powerband. In street and track performance engines, longer header tubes typically produce more low-to-mid range torque than shorter tubes and it is torque that moves a vehicle. This begs the question... Where in the powerband do you want to maximize torque?

• Longer header tubes tend to increase power below the engine’s torque peak and shorter header tubes tend to increase power above the torque peak.
• Large diameter headers and collectors tend to limit low-range power and increase high range power.
• Small diameter headers and collectors tend to increase low-range power and limit high-range power.
• "Balance" or "equalizer" tubes between the collectors tend to flatten the torque peak(s) and widen the powerband.

There is limited space in most engine compartments for header tubes and equal length tubes complicate the design process and are more costly to build than "convenient" length or cosmetic headers. Exhaust header designers are severely compromised by these limitations. Among the more astute (and responsible) professional header builders, it is more-or-less understood that header tube length variations should not exceed 1" to be considered equal. Even this standard can result in a 2" difference if one tube is an inch short and another tube is an inch long. By this definition, equal length headers are quite rare. By absolute measurement, it is probably impossible to find equal length headers from a commercial manufacturer. Because of this, it is no surprise that many people have little knowledge of the benefits of equal length headers since the average user is unlikely to have experience with them. If you have headers that are supposedly equal length, carefully measure each tube and you will know the truth.
________________________________________
Exhaust Scavenging

Inertial scavenging and wave scavenging are different phenomena but both impact exhaust system efficiency and affect one another. Scavenging is simply gas extraction. These two scavenging effects are directly influenced by tube diameter, length, shape and the thermal properties of the tube material (stainless, mild steel, cast iron, etc.). When the exhaust valve opens, two things immediately happen. An energy wave, or pulse, is created from the rapidly expanding combustion gases. The wave enters the header tube (or manifold) traveling outward at a nominal speed of 1,300 - 1,700 feet per second (this speed varies depending on engine design, modifications, etc., and is therefore stated as a "nominal" velocity). This wave is pure energy, similar to a shock wave from an explosion. Simultaneous with the energy wave, the spent combustion gases also enter the head tube and travel outward more slowly at 150 - 300 feet per second nominal (maximum power is usually made with gas velocities between 240 and 300 feet per second). Since the energy wave is moving about 5 times faster than the exhaust gases, it will get where it is going faster than the gases. When the outbound energy wave encounters a lower pressure area such as a larger collector pipe, muffler or the ambient atmosphere, a reversion wave (a reversed or mirrored wave) is reflected back toward the exhaust valve without significant loss of velocity.

The reversion wave moves back toward the exhaust valve on a collision course with the exiting gases whereupon they pass through one another, with some energy loss and turbulence, and continue in their respective directions. What happens when that reversion wave arrives at the exhaust valve depends on whether the valve is still open or closed. This is a critical moment in the exhaust cycle because the reversion wave can be beneficial or detrimental to exhaust flow, depending upon its arrival time at the exhaust valve. If the exhaust valve is closed when the reversion wave arrives, the wave is again reflected toward the exhaust outlet and eventually dissipates its energy in this back and forth motion. If the exhaust valve is open when the wave arrives, its effect upon exhaust gas flow depends on which part of the wave is hitting the open exhaust valve.

A wave is comprised of two alternating and opposing pressures. In one part of the wave cycle, the gas molecules are compressed. In the other part of the wave, the gas molecules are rarefied. Therefore, each wave contains a compression area (node) of higher pressure and a rarefaction area (anti-node) of lower pressure. An exhaust tube of the proper length (for a specific RPM range) will place the wave’s anti-node at the exhaust valve at the proper time for it’s lower pressure to help fill the combustion chamber with fresh incoming charge and to extract spent gases from the chamber. This is wave scavenging or "wave tuning".
From these cyclical engine events, one can deduce that the beneficial part of a rapidly traveling reversion wave can only be present at an exhaust port during portions of the powerband since it's relative arrival time changes with RPM. This makes it difficult to tune an exhaust system to take advantage of reversion waves which is why there are various anti-reversion schemes designed into some header systems and exhaust ports. These anti-reversion devices are designed to weaken and disrupt the detrimental reversion waves (when the wave's higher-pressure node impedes scavenging and intake draw-through). Anti-reversion schemes include merge collectors, truncated cones/rings built into the primary tube entrance and exhaust port ledges.
Unlike reversion waves that have no mass, exhaust gases do have mass. And since they are in motion, they also have inertia (or "momentum") as they travel outward at their comparatively slow velocity of 150 - 300 fps. When the gases move outward as a gas column through the header tube, a decreasing pressure area is created in the pipe behind them. It may help to think of this lower pressure area as a partial vacuum and one can visualize the vacuous lower pressure "pulling" residual exhaust gases from the combustion chamber and exhaust port. It can also help pull fresh air/fuel charge into the combustion chamber. This is inertial scavenging and it has a major effect upon engine power at low-to-mid range RPM.

If properly timed with RPM and firing order, the low pressure that results from gas inertia can spill-over into other primary tubes, via the collector, and aid the scavenging of other cylinders in that bank.
There are other factors that further complicate the behavior of exhaust gases. Wave harmonics, wave amplification and wave cancellation effects also play into the scheme of exhaust events. The interaction of all these variables is so abstractly complex that it is difficult to fully grasp. The author is not aware of any absolute formulas/algorithms that will produce a perfect exhaust design. Even factory super-computer exhaust designs must undergo dynamometer and track testing to determine the necessary adjustments for the desired results. Although there are some exhaust design software packages available, the author has found none that embrace all aspects of exhaust physics.
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The Effects of Tube Size

Statistical Approximations for a Typical 350" GM V-8 Engine
Horsepower > 300 - 375 375 - 475 475 - 580
Header Tube Diameter > 1.625" 1.75" 1.875"
Collector Tube Diameter for Max Low-RPM Power > 2.5" 2.75" 3"
Collector Tube Diameter for Max Mid-RPM Power > 2.75" 3" 3.25"
Collector Tube Diameter for Max High-RPM Power > 3" 3.25" 3.5"
Tube dimensions (as opposed to "pipe" dimensions) are measured by Outside Diameter (OD).
Tube Inside Diameter (ID) is determined by subtracting the tube wall thickness (x 2) from the OD.
__________________

 

I have had LG headers,flp,kooks,and one other I cant remember.when my car was a 346 ci motor I will have to say the LG headers were better than the flp but not by much I loved the flp headers because they had removable cats.Now with the 434 ci motor hands down I would go with the kooks headers and yes I have done back to back dyno testing with LG and kooks on a big motor the primary tubes are to long for a motor that realy breathes a lot of air. just my .02$

 

Aside from a pretty big difference in price what is the difference between LG pro and "non" pro? I checked their site and really don't see an explanation.

 

Holy Cow somebody who understands how it works! Should make that a 1st read sticky for any auto forum.

I get so tired of "...made 402 hp to the wheels..." posts where no rpm, graph, or torque curve is mentioned. Absolutely worthless. Let's see the whole curve. Unless you're running and F1 car between 17-19,000 rpm with a 7 speed ultra close ratio gear box, average torque is where it's at, especially for a 3-4k lb street car.

 

Charlie is VERY knowledgable, he did the tuning on my car and I have to say I couldn't be happier with his work. How do you argue with that much experience.